Agriculture plays a central role in Sierra Leone’s economy, with approximately two-thirds of the population relying on it for their livelihood. Among various agricultural activities, cocoa production stands out as a promising avenue for increasing rural incomes, particularly in the Eastern region. However, producers face complex marketing choices that influence their income and the overall development of the cocoa sector. This study investigates the marketing behavior of cocoa producers in Sierra Leone through the lens of New Institutional Economics, specifically applying the Power Resources concept alongside Value Chain Analysis. Employing both qualitative and quantitative methods, the research included 20 Focus Group Discussions and surveys with 100 cocoa farmers across selected Eastern Province communities. Twelve Power Resources were assessed, with findings indicating that those associated with transaction costs, risk exposure, exit barriers, sanction power, and credibility have the greatest impact on marketing decisions. Farmers preferred selling to cooperatives due to reduced transaction costs, lower risks, and more reliable commitments. In contrast, they avoided petty traders and Lebanese buyers because of high price volatility, limited market information, and fears of exploitation. High exit costs also characterized relationships with companies and Lebanese buyers, due to dependency and a lack of alternative markets. Additionally, the weak sanction power of farmers influenced a preference for resident buyers, who are subject to traditional authority. Overall, the study concludes that Power Resource endowments significantly shape marketing behavior, encouraging sales to cooperatives while deterring engagement with less trustworthy market actors. These insights support the role of cooperatives in promoting fair trade, quality production, and sustainable income growth.